Evaluator.java won't compile due to issues with javax.tools.*

Question

* Evaluator.java
* Created on January 23, 2007, 4:17 PM
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* and open the template in the editor.
package ObjectTools;
import java.io.*;
import java.net.*;
import javax.tools.*;
import java.lang.reflect.*;
* Utilizes {@link java.lang.reflect} package
* @author ppowell-c
public abstract class Evaluator {
    public static boolean writeSource(final String sourcePath, final String sourceCode)
    throws FileNotFoundException {
        PrintWriter writer = new PrintWriter(sourcePath);
        writer.println(sourceCode);
        writer.close();
        return true;
    public static boolean compile(final String sourcePath) throws IOException {
        final JavaCompilerTool compiler = ToolProvider.defaultJavaCompiler();
        final JavaFileManager manager = compiler.getStandardFileManager();
        final JavaFileObject source =
                manager.getFileForInput(sourcePath); /* java.io.IOException */
        final JavaCompilerTool.CompilationTask task = compiler.run(null, source);
        return task.getResult();
    public static final java.lang.Class loadExpression(final String path, final String className)
    throws MalformedURLException,
            ClassNotFoundException { /* java.net.MalformedURLException */
        final URLClassLoader myLoader = new URLClassLoader(new java.net.URL[] {
            new File(path).toURI().toURL()
        /* java.lang.ClassNotFoundException */
        return Class.forName(className, true, myLoader);
    public static java.lang.Object evalExpression(final Class test)
    throws NoSuchMethodException, IllegalAccessException, InvocationTargetException {
        final Class[] parameterType = null;
        /* java.lang.NoSuchMethodException */
        final Method method = test.getMethod("expression", parameterType);
        final Object[] argument = null;
        Object instance = null;
        /* java.lang.IllegalAccessException, java.lang.reflect.InvocationTargetException */
        return method.invoke(instance, argument);
    public static Object eval(final String expression)
    throws FileNotFoundException, IOException, MalformedURLException,
            ClassNotFoundException, NoSuchMethodException, IllegalAccessException,
            InvocationTargetException {
        final Object result;
        final String path = "c:/";
        final String className = "ExpressionWrapper";
        final String sourcePath = path + className + ".java";
        writeSource(/* to */ sourcePath,
                "public class " + className + "\n" +
                "{ public static java.lang.Object expression()\n" +
                "  { return " + expression + "; }}\n" );
        if(compile(sourcePath)) {
            final Class class_ =
                    loadExpression(/* from */ path, className);
            result = evalExpression(class_);
        } else {
            result = null;
        return result;
}Produces compiler errors on javax.tools.ToolProvider along with nearly everything else in javax.tools to boot.
I'm using J2SE 1.5.0 with NetBeans 5.5 so they all should be there. I'm following the example at http://userpage.fu-berlin.de/~ram/pub/pub_jf47ht9Ht/evaluating-expressions-with-java since all I want to do is come up with a Java equivalent of "eval()", which I use in PHP whenever I need it.
Help appreciated, I'm lost here.
Thanx
Phil

Answer 1

How do you do the Java equivalent of eval()?The language provides no support for that.
Reflection lets you call any method, where you
specify that method's name as a string and go through
a few other steps to build the proper Method object
with the proper args.
(http://java.sun.com/docs/books/tutorial/reflect/) It
won't let you just evaluate Java source code as a
script interpreter though. To do that, see
www.beanshell.org. Jython and I think Ruby on Rails
also give you scriptingin Java. Jython uses Python's
syntax, but gives you access to your Java classes. I
don't know ayhthing about RoR.I am going to look up PHP/Java myself as I know no Python right offhand (but probably could learn it in about 10,000 years). Tried to figure out reflection but couldn't figure out how to do what in PHP we do like this:
$msg = eval('JButton ' . $nameArray[$i][0] . ' = new JButton("' . $nameArray[$i][1] . '");');